A tunnel vent structure construction method under soft surrounding rock conditions

Abstract

The present invention discloses a method for constructing a tunnel vent structure under soft surrounding rock conditions. The vent structure adopts a "side expansion type" cross-connection type, and the excavation sections all adopt curved walls or arched sections. There is no interference between the connecting channel and the main tunnel excavation, and there is no gradual section in the excavation; the widened section is the same as the tunnel emergency parking strip section, and the emergency parking strip lining trolley and template can be used; the connecting channel assists the active excavation operation, which can increase the main tunnel excavation operation surface and save construction time. When the vent structure is located in soft surrounding rock and it is necessary to enter the main tunnel from the connecting channel to assist the main tunnel excavation, the construction method of the present invention is used to construct the vent structure, which can obtain better safety protection and construction effect.

Description

Technical Field

[0001] The invention relates to the technical field of tunnel engineering, and in particular to a method for constructing a tunnel vent structure under soft surrounding rock conditions. Background Art

[0002] Due to the needs of disaster prevention, rescue and driving comfort, most highway tunnels are equipped with ventilation shafts (vertical shafts or inclined shafts) for ventilation. Underground, the tunnel and the ventilation shaft are connected by a communication channel. The construction method of the tunnel ventilation structure in the prior art is: dig a certain height above the main hole of the intersection section to send wind into the tunnel or extract smoke and dust out of the main hole. This construction method has the following main shortcomings:

[0003] (1) Complex construction. It is difficult to excavate the intersection in one go, and it is usually necessary to construct the connecting passage or the main tunnel first. If the connecting passage is constructed first, the arch connecting passage may collapse when the main tunnel is excavated; if the main tunnel is constructed first, the lining of the main tunnel arch ventilation opening needs to be removed after the connecting passage is constructed.

[0004] (2) High construction risk and low structural safety. Due to multiple excavation interferences, the excavated support structure is prone to cracking and instability; there are many straight wall structures at the intersection, which is not conducive to structural stress and has low structural safety.

[0005] (3) It is not conducive to assisting the main tunnel excavation operation. Extra-long tunnels are large in scale and have a tight construction schedule. Vertical and inclined shafts (especially inclined shafts) usually also serve as auxiliary construction channels for the main tunnel to assist the main tunnel excavation operation and speed up the construction progress. Traditional solutions make it difficult for construction vehicles to freely enter and exit the main tunnel, making it difficult to serve as an effective auxiliary construction channel for the main tunnel.

[0006] Therefore, it is necessary to propose an improved construction method of tunnel ventilation structure to solve the above technical problems. Summary of the invention

[0007] In view of the defects in the prior art, the object of the present invention is to provide a method for constructing a tunnel vent structure under soft surrounding rock conditions.

[0008] According to one aspect of the present invention, a method for constructing a tunnel vent structure under soft surrounding rock conditions is provided, comprising:

[0009] Excavate the rock mass on the upper step of the communication channel and provide initial support for the upper step of the communication channel;

[0010] The widened upper step rock mass within the width of the arched pilot tunnel excavation communication channel is used for initial support of the arched pilot tunnel;

[0011] Spray concrete backfills the cavity between the arch of the pilot pit and the initial support of the widened band, and constructs the initial support of the upper step of the widened band of the pilot pit section;

[0012] Excavate the widened upper step rock mass at both ends, and construct the initial support for the widened upper step at both ends;

[0013] Excavate the rock mass of the step below the communication channel and the rock mass on the right side of the widened middle step within the width of the communication channel, and provide initial support for the step below the communication channel;

[0014] Excavate the rock mass on the right side of the middle step of the widened area towards both ends, and provide initial support on the right side of the middle step of the widened area;

[0015] Excavate the rock mass on the left side of the middle step of the widened belt, and construct the initial support on the left side of the middle step of the widened belt;

[0016] Excavate the rock mass on the left side of the step below the widened area and the rock mass on the right side of the step below the widened area, construct the initial support on the left side of the step below the widened area and the initial support on the right side of the step below the widened area, and construct the initial support for the widened arch at the bottom;

[0017] Construct the secondary lining of the widened invert at the bottom and the backfill of the widened invert;

[0018] Excavate the rock mass of the general section of the main tunnel at both ends, and apply corresponding initial support for the general section of the main tunnel;

[0019] Construct the secondary lining of the widened arch and side walls and the secondary lining of the communication passage, and construct the secondary lining of the general section of the main tunnel;

[0020] According to the ventilation function requirements of the ventilation holes, construct the main hole lining for ventilation holes;

[0021] The main hole lining for the ventilation outlet is constructed according to the requirements of the ventilation outlet's air supply function.

[0022] Furthermore, the communication channel is arranged on the same side as the ventilation shaft, the communication channel is arranged on the same side as the widened band, the communication channel intersects with the outline of the widened band, and the main tunnel hole is provided with an exhaust structure or an air supply structure at the intersection with the axis of the communication channel.

[0023] Furthermore, the inner contour of the widened strip is the same as the inner contour of the tunnel emergency stop strip.

[0024] Furthermore, the initial support in the method includes steel support, steel mesh and shotcrete, the secondary lining is a reinforced concrete structure, and the backfill of the invert is low-grade plain concrete.

[0025] Furthermore, the arched guide pit is excavated on the widened upper step rock mass within the width of the connecting channel, and the initial support of the arched guide pit is applied, including: the top of the guide pit adopts an arched section, the top of the guide pit is higher than the widened initial support, and the arch ring rise-span ratio of the top of the guide pit is 1 / 10.

[0026] Furthermore, after the initial support of the arched guide pit is applied to the stepped rock mass on the widened band within the width of the arched guide pit excavation connecting channel, the following steps are performed: a steel beam is applied at the intersection of the connecting channel and the widened band; the steel beam adopts a steel structure, and the cross-sectional shape of the steel is determined according to force calculation; the steel beam is fixed to the arch top of the connecting channel opening by a locking anchor rod, and the locking anchor rod adopts a Φ25 mortar anchor rod or a D42 grouting small tube.

[0027] Furthermore, the steel supports in the widened initial support within the range of the communication channel stand on the steel crossbeam on the communication channel side, and the steel supports are connected to the steel crossbeam by welding.

[0028] Furthermore, the excavating of the rock mass on the left side of the step below the widened band and the rock mass on the right side of the step below the widened band comprises: staggered excavation of the rock mass on the left side of the step below the widened band and the rock mass on the right side of the step below the widened band.

[0029] Furthermore, the construction of the widened arch and side wall secondary lining and the connecting channel secondary lining includes: when constructing the widened secondary lining, determining the main tunnel lining type according to the exhaust function or air supply function of the vent, and pre-embedding steel bars at the joint of the two linings.

[0030] Furthermore, the inner contours of the excavation all adopt curved walls or arched sections.

[0031] Compared with the prior art, the present invention has at least one of the following beneficial effects:

[0032] 1. The present invention adopts a "side expansion type" cross-connection type, and the excavation sections all adopt curved walls or arched sections. There is no interference between the connecting channel and the main hole excavation, and there is no gradual section in the excavation, which is conducive to the stability of the surrounding rock, convenient construction, and high safety.

[0033] 2. The present invention can realize one-time excavation and forming of the intersection of the main tunnel and the connecting channel. The construction method is simple. Each step of excavation and support is of conventional section and common materials. There is no gradual size, and no special equipment, machinery and templates are required. The tedious processing of gradual structural materials is eliminated, labor and effort are saved, and the construction speed is fast, which is conducive to improving construction quality and saving investment.

[0034] 3. The stratum applicability of the present invention is wide. When the ventilation opening structure is located in the IV and V grade soft surrounding rock sections, the construction method of the present invention can obtain better safety guarantee. When the ventilation opening structure is located in the better grade III and above surrounding rock, the construction method of the present invention can still be used to simplify the excavation of the connecting channel from the upper and lower step method to the full section method, and simplify the excavation of the widened upper, middle and lower step method to the upper and lower step method, thereby improving construction efficiency.

[0035] 4. The widened strip section of the present invention is the same as the cross section of the tunnel emergency stop strip, and the emergency stop strip lining trolley and template can be used without additional construction measures.

[0036] 5. The present invention assists active excavation operations through communication channels, which can increase the main tunnel excavation operation surface and save construction time. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0038] Figure 1 This is a schematic diagram of the structure corresponding to step S1 in an embodiment of the present invention;

[0039] Figure 2 This is a schematic diagram of the structure corresponding to step S2 in an embodiment of the present invention;

[0040] Figure 3 for Figure 2 The enlarged schematic diagram corresponding to point A in the middle;

[0041] Figure 4 This is a schematic diagram of the structure corresponding to step S3 in an embodiment of the present invention;

[0042] Figure 5 This is a schematic diagram of the structure corresponding to step S4 in an embodiment of the present invention;

[0043] Figure 6 This is a schematic diagram of the structure corresponding to step S5 in an embodiment of the present invention;

[0044] Figure 7 This is a schematic diagram of the structure corresponding to step S6 in an embodiment of the present invention;

[0045] Figure 8 This is a schematic diagram of the structure corresponding to step S7 in an embodiment of the present invention;

[0046] Fig. 9 This is a schematic diagram of the structure corresponding to step S8 in an embodiment of the present invention;

[0047] Fig.10 This is a schematic diagram of the structure corresponding to step S9 in an embodiment of the present invention;

[0048] Fig.11 This is a schematic diagram of the structure corresponding to step S10 in an embodiment of the present invention;

[0049] Fig.12 This is a schematic diagram of the structure corresponding to step S11 in an embodiment of the present invention;

[0050] Fig.13 This is a schematic diagram of the structure corresponding to step S12 in an embodiment of the present invention;

[0051] Fig.14 This is a schematic diagram of the structure corresponding to step S13 in an embodiment of the present invention;

[0052] Fig.15 It is a schematic diagram of the structure of excavation support in an embodiment of the present invention;

[0053] Fig.16 In the embodiment of the present invention Fig.15 The corresponding II cross-sectional schematic diagram;

[0054] Fig.17 In the embodiment of the present invention Fig.15 The corresponding II-II cross-sectional view.

[0055] In the figure, Ⅰ-1 is the rock mass of the upper step of the communication channel, Ⅰ-2 is the rock mass of the lower step of the communication channel, Ⅱ is the rock mass of the upper step of the widened band, Ⅲ-1 is the rock mass on the left side of the middle step of the widened band, Ⅲ-2 is the rock mass on the right side of the middle step of the widened band, Ⅳ-1 is the rock mass on the left side of the lower step of the widened band, Ⅳ-2 is the rock mass on the right side of the lower step of the widened band, Ⅴ is the rock mass of the general section of the main tunnel, 1a is the initial support of the upper step of the communication channel, 1b is the initial support of the lower step of the communication channel, 2 is the initial support of the arched pilot pit, 3 is the cavity between the arch of the pilot pit and the initial support of the widened band, 4a is a steel beam, 4b is a locking anchor rod, and 4c is the reinforcement. The initial support for the upper step of the wide band, 5a is the initial support for the left side of the middle step of the wide band, 5b is the initial support for the right side of the middle step of the wide band, 6a is the initial support for the left side of the lower step of the wide band, 6b is the initial support for the right side of the lower step of the wide band, 7 is the initial support for the widened arch, 8 is the secondary lining of the widened arch, 9 is the backfill of the widened arch, 10 is the secondary lining of the arch and side wall of the widened band, 11 is the secondary lining of the connecting passage, 12 is the initial support of the general section of the main tunnel, 13 is the secondary lining of the general section of the main tunnel, 14 is the main tunnel lining for the exhaust function of the vent, and 15 is the main tunnel lining for the supply function of the vent. DETAILED DESCRIPTION

[0056] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention. In the description of the embodiments of the present invention, it should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein.

[0057] The embodiment of the present invention provides a method for constructing a tunnel vent structure under soft surrounding rock conditions. Figure 1-17 , the method comprising:

[0058] S1. Excavate the rock mass Ⅰ-1 on the upper step of the communication channel and carry out the initial support 1a on the upper step of the communication channel.

[0059] In some preferred embodiments, the communication channel is arranged on the same side as the ventilation shaft, the communication channel is arranged on the same side as the widened band, the communication channel intersects with the outline of the widened band, and the main tunnel of the tunnel is provided with an exhaust structure or an air supply structure at the intersection of the axis of the communication channel. The inner outline of the widened band is the same as the inner outline of the tunnel emergency parking strip.

[0060] S2. For the widened upper step rock mass II within the width of the arched pilot tunnel excavation communication channel, initial support 2 of the arched pilot tunnel shall be implemented.

[0061] In some preferred embodiments, after the initial support of the arched pilot pit is applied to the widened upper step rock mass within the width of the connecting channel in the arched pilot pit, the following steps are included: a steel beam is applied at the intersection of the connecting channel and the widened upper step rock mass, such as Figure 2 The steel crossbeam 4a of the arch of the communication passage opening is shown; the steel crossbeam adopts a steel structure, and the cross-section type of the steel is determined according to the force calculation; the steel crossbeam is fixed to the arch of the communication passage opening by a locking anchor rod 4b, and the locking anchor rod adopts a Φ25 mortar anchor rod or a D42 grouting small tube.

[0062] The steel supports in the widened initial support within the communication channel are erected on the steel beams on the communication channel side, and the steel supports and the steel beams are connected by welding.

[0063] In some preferred embodiments, the widened upper step rock mass within the width of the arched guide pit excavation communication channel is subjected to initial support of the arched guide pit, including: the top of the guide pit adopts an arched section, the top of the guide pit is higher than the widened initial support, and the arch ring rise-span ratio of the top of the guide pit is about 1 / 10. Technical personnel in this field can make any appropriate adjustments according to actual needs.

[0064] S3, backfill the cavity 3 between the arch of the pilot pit and the initial support of the widened band with shotcrete, and construct the initial support 4c of the upper step of the widened band of the pilot pit section;

[0065] S4, excavate the widened upper step rock mass II at both ends, and construct the widened upper step initial support 4c at both ends;

[0066] S5. Excavate the rock mass Ⅰ-2 of the step below the communication channel and the rock mass Ⅲ-2 on the right side of the step in the widened width within the width of the communication channel, and construct the initial support 1b of the step below the communication channel;

[0067] S6. Excavate the rock mass III-2 on the right side of the middle step of the widened belt towards both ends, and construct the initial support 5b on the right side of the middle step of the widened belt;

[0068] S7. Excavate the rock mass III-1 on the left side of the middle step of the widened belt, and carry out the initial support for 5a on the left side of the middle step of the widened belt; stagger the rock mass on the left side of the middle step of the widened belt and the rock mass on the right side of the middle step of the widened belt to avoid simultaneous bottoming;

[0069] S8. Excavate the rock mass IV-1 on the left side of the lower step of the widened band and the rock mass IV-2 on the right side of the lower step of the widened band, construct the initial support 6a on the left side of the lower step of the widened band and the initial support 6b on the right side of the lower step of the widened band, construct the initial support 7 of the widened band invert at the bottom, and stagger the left and right sides of the rock mass IV-1 on the left side of the lower step and the rock mass IV-2 on the right side of the lower step to avoid falling to the bottom at the same time;

[0070] S9, constructing the secondary lining 8 of the widened invert at the bottom and the backfill 9 of the widened invert;

[0071] S10, excavate the rock mass V of the general section of the main tunnel towards both ends, and implement the corresponding initial support 12 of the general section of the main tunnel;

[0072] S11. Construct the secondary lining 10 of the widened arch and side walls and the secondary lining 11 of the connecting passage, and construct the secondary lining 13 of the general section of the main tunnel. When constructing the widened secondary lining, determine the main tunnel lining type based on the exhaust function or air supply function of the vents, and pre-embed steel bars at the joints of the two linings.

[0073] S12. Construct the main tunnel lining 14 of the ventilation outlet according to the ventilation outlet exhaust function requirements.

[0074] S13. Construct the main tunnel lining 15 of the ventilation outlet according to the ventilation outlet air supply function requirements.

[0075] In some preferred embodiments, the initial support in the above method includes steel support, steel mesh and shotcrete, the secondary lining is a reinforced concrete structure, and the arch backfill is low-grade plain concrete.

[0076] In the construction method in the embodiment of the present invention, the inner contour of the excavation adopts curved walls or arched sections. The construction technology and method are mature, which is beneficial to the stability of the surrounding rock and the stress of the structure, and avoids the existence of more straight wall excavation sections and mutual interference in traditional construction methods. The method is simple, safe and widely applicable.

[0077] In the embodiment of the present invention, the cross-sectional size of the communication channel needs to be determined according to the ventilation requirements and the construction equipment requirements, and the cross-sectional profile of the vehicle passage can generally be adopted. The communication channel is excavated by the upper and lower steps method, which can reduce the cross-sectional area of ​​a single excavation and is conducive to the stability of the surrounding rock.

[0078] In the embodiment of the present invention, the length range of the widened width excavated at both ends is determined by the length of the ventilation opening structure. The length of the general section rock mass of the main tunnel excavated at both ends and the length of the corresponding initial support are determined according to the construction organization and the space required for the trolley assembly.

[0079] In the embodiment of the present invention, the cross section of the widened belt is the same as the cross section of the tunnel emergency parking belt, and the emergency parking belt lining trolley and template can be used without additional construction measures.

[0080] In the embodiment of the present invention, the widened band has a large cross-section, which is beneficial for assisting the main tunnel excavation vehicle to turn around during construction.

[0081] When the ventilation opening structure is located in an area with good surrounding rock of grade III or above, step S2 of the method of the present invention may not use the widened upper step III within the width of the arch excavation communication channel, and the top may be consistent with the outer contour of the widened arch portion, and excavated in place at one time.

[0082] The construction method in the above-mentioned embodiment of the present invention adopts a "side expansion type" cross-connection type, and the excavation sections all adopt curved walls or arch sections. There is no interference between the connecting channel and the main tunnel excavation, and there is no gradual section in the excavation, which is conducive to the stability of the surrounding rock, convenient construction, and high safety.

[0083] The embodiment of the present invention can realize one-time excavation and shaping of the intersection of the main tunnel and the connecting channel. The construction method is simple. Each step of excavation and support is of conventional cross-section and common materials, without gradient size, and does not require special equipment, machinery and templates. The cumbersome processing of gradient structural materials is eliminated, labor and effort are saved, and the construction speed is fast, which is conducive to improving construction quality and saving investment. Moreover, by assisting the active excavation operation through the connecting channel, the main tunnel excavation operation surface can be increased, which greatly saves construction time.

[0084] The construction method in the embodiment of the present invention has wide applicability to strata. When the ventilation hole structure is located in the IV or V grade soft surrounding rock section, the construction method of the present invention can be used to obtain better safety guarantee. When the ventilation hole structure is located in the better grade III or above surrounding rock, the construction method of the present invention can still be used to simplify the excavation of the connecting channel from the upper and lower step method to the full section method, and simplify the excavation of the widened upper, middle and lower step method to the upper and lower step method, thereby improving construction efficiency.

[0085] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various modifications or variations within the scope of the claims, which does not affect the essence of the present invention. The above preferred features can be used in any combination without conflicting with each other.

Claims

1. A method for constructing a tunnel vent structure under soft surrounding rock conditions, characterized in that: include: S1. Excavate the rock mass on the upper step of the communication channel and provide initial support for the upper step of the communication channel; S2. Excavate the widened upper step rock mass within the width of the arched pilot tunnel, and apply the initial support of the arched pilot tunnel; S3. Spray concrete backfilling the cavity between the arch of the pilot pit and the initial support of the widened belt, and constructing the initial support of the upper step of the widened belt of the pilot pit section; S4. Excavate the widened upper step rock mass at both ends and provide initial support for the widened upper step at both ends; S5. Excavate the rock mass of the step below the communication channel and the rock mass on the right side of the step in the widened width within the width of the communication channel, and provide initial support for the step below the communication channel; S6. Excavate the rock mass on the right side of the middle step of the widened belt towards both ends, and provide initial support on the right side of the middle step of the widened belt; S7. Excavate the rock mass on the left side of the middle step of the widened belt and construct the initial support on the left side of the middle step of the widened belt; S8. Excavate the rock mass on the left side of the step below the widened area and the rock mass on the right side of the step below the widened area, construct the initial support on the left side of the step below the widened area and the initial support on the right side of the step below the widened area, and construct the initial support for the widened arch at the bottom; S9, construct the secondary lining of the widened invert at the bottom and backfill the widened invert; S10, excavate the rock mass of the general section of the main tunnel towards both ends, and apply corresponding initial support for the general section of the main tunnel; S11. Construct the secondary lining of the widened arch and side walls and the secondary lining of the communication passage, and construct the secondary lining of the general section of the main tunnel; S12. Construct the main hole lining of the ventilation outlet according to the ventilation outlet exhaust function requirements; S13. Construct the main tunnel lining of the ventilation outlet according to the ventilation outlet air supply function requirements.

2. The method for constructing a tunnel vent structure under soft surrounding rock conditions according to claim 1, characterized in that: The communication channel is arranged on the same side as the ventilation shaft, the communication channel is arranged on the same side as the widened band, the communication channel intersects with the outline of the widened band, and the main tunnel hole is provided with an exhaust structure or an air supply structure at the intersection with the axis of the communication channel.

3. The method for constructing a tunnel vent structure under soft surrounding rock conditions according to claim 1, characterized in that: The inner contour of the widened strip is the same as the inner contour of the tunnel emergency stop strip.

4. The method for constructing a tunnel vent structure under soft surrounding rock conditions according to claim 1, characterized in that: The initial support in the method includes steel support, steel mesh and shotcrete, the secondary lining is a reinforced concrete structure, and the backfill of the invert is low-grade plain concrete.

5. The method for constructing a tunnel vent structure under soft surrounding rock conditions according to claim 1, characterized in that: The arched guide pit excavates the widened upper step rock mass within the width of the connecting channel, and applies initial support to the arched guide pit, including: the top of the guide pit adopts an arched section, the top of the guide pit is higher than the widened initial support, and the arch ring rise-span ratio of the top of the guide pit is 1 / 10.

6. The method for constructing a tunnel vent structure under soft surrounding rock conditions according to claim 1, characterized in that: After the initial support of the arched guide pit is applied to the stepped rock mass on the widened band within the width of the arched guide pit excavation connecting channel, the following steps are performed: a steel beam is applied at the intersection of the connecting channel and the widened band; the steel beam adopts a steel structure, and the cross-section type of the steel is determined according to force calculation; the steel beam is fixed to the arch top of the connecting channel opening by a locking anchor rod, and the locking anchor rod adopts a Φ25 mortar anchor rod or a D42 grouting small tube.

7. The method for constructing a tunnel vent structure under soft surrounding rock conditions according to claim 6, characterized in that: The steel supports in the widened initial support within the communication channel are erected on the steel beams on the communication channel side, and the steel supports are connected to the steel beams by welding.

8. The method for constructing a tunnel vent structure under soft surrounding rock conditions according to claim 1, characterized in that: The excavation of the left rock mass of the step below the widened band and the right rock mass of the step below the widened band comprises: staggered excavation of the left rock mass of the step below the widened band and the right rock mass of the step below the widened band.

9. The method for constructing a tunnel vent structure under soft surrounding rock conditions according to claim 1, characterized in that: The construction of the widened arch and side wall secondary lining and the communication channel secondary lining includes: when constructing the widened secondary lining, determining the main tunnel lining type according to the exhaust function or air supply function of the vent, and pre-embedding steel bars at the joint of the two linings.

10. The method for constructing a tunnel vent structure under soft surrounding rock conditions according to claim 1, characterized in that: The inner contour of the excavation adopts curved wall or arch section.

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